The performance of antenna systems, for example in the field of mobile communications, depends on the signal quality of the radio frequency signals sent and received by the antenna. It is desirable to have sufficient performance for all users in an area covered by an antenna beam of the antenna system. The orientation of such an antenna beam is adjustable, for example by varying the tilt of the antenna.
With remotely located electrical tilt systems or electromechanical tilt mechanisms it is only possible to experiment with a new tilt setting by actually trying the new tilt and potentially suffering a detriment in coverage or quality of service for the users during the experiment. Changes to the tilt angle are therefore typically performed at infrequent intervals, for example in spring, when leaves appear on trees and in autumn, when the leaves fall off the trees. The experimental settings of the tilt angle are usually based upon recommendations given by a network coverage planning tool. In many cases the tilt angles chosen by such coverage planning tools are suboptimal, due to their imperfect knowledge of the environment of the cell served by the antenna system. Furthermore, in an existing network with already deployed antenna systems only the tilt setting can be changed by using the electrical tilt systems or electromechanical tilt mechanisms. In active antenna systems, beam forming of the antenna beam is performed by applying a specific antenna pattern. For example, a beam forming vector or a steering vector which controls the phase and/or the amplitude of the signals transmitted by each single antenna of the antenna system, determines the specific antenna pattern.
Although the orientation of the antenna beam can be varied using the electrical tilt systems or electromechanical tilt mechanisms, the prior art antenna systems do not provide the possibility to experiment with a new or different antenna pattern at an antenna site, without disturbing the existing coverage and quality of service during the experiment.